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Spectroscopic properties of push-pull 2-(4-carboxyphenyl)-6-dimethylaminobenzothiazole derivatives in solution and the solid state
摘要： 6-Dimethylamino-2-phenylbenzothiazoles with a carboxy, ester and amide substituent on the 2-phenyl group were prepared as a series of the push-pull benzothiazoles, and their spectroscopic and photophysical properties in solutions were investigated. The derivatives showed solvatochromic fluorescence with quantum yields over 0.68 in various organic solvents similar to the core fluorophore structure. The color variation ranges in fluorescence solvatochromism of the derivatives were wider than that of the original compound having the core structure, 6-dimethylamino-2-phenylbenzothiazole. It was also found that the derivatives together with the original compound show solid state fluorescence depending on their crystal structures. In particular, an ester derivative with a protected serine has a reasonable crystal packing leading to increase in fluorescence efficiency. The results of the present study provide a guide to design push-pull 2-phenylbenzothiazoles exhibiting fluorescence in solution and the solid state.
关键词： Substituent effect,Firefly oxyluciferin,Fluorescence solvatochromism,Solid state fluorescence,Benzothiazole
更新于2025-11-19 16:56:35
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2-(1,1-dioxidobenzo[b]thiophen-3(2H)-ylidene)malononitrile (BTD) Based Styryl Chromophores- Solvatochomic and Computational Investigation of Linear and NLO properties
摘要： Linear and nonlinear optical properties of the twelve styryl dyes are investigated using density functional theory (DFT). Range-separated hybrid CAM-B3LYP and global hybrid BHandHLYP estimate high second order hyperpolarizability. Mean polarizability (α0), polarizability anisotropy (Δα), static first-order hyperpolarizability (β0) and second hyperpolarizability (γ) were found to be overestimated in CAM-B3LYP than in BHandHLYP. As bond length alternation (BLA) increases first order hyperpolarizability increases. Multilinear regression analysis (MLR) shows the solvent basicity, polarizability and dipolarizability are responsible for absorption solvatochromism. The ratio of the dipole moments increases as donor strength and conjugation increases which support charge transfer. The figure of merit (FOM) and intrinsic hyperpolarizability found more in chromophores with dialkylamine donors. As the stability indicated by electrophilicity indices decreases the hyperpolarizability increases. Interrelationships between α0, β0 and γ were evaluated and it shows good linear fit. Absorption is red shifted and hyperpolarizability increases with the amplitude of the sine-shaped potential along the conjugation chain. A high molecular electrostatic potential was observed in dyes containing 2-piperidinothiophene donor.
关键词： NLO,Charge transfer,DFT and TD-DFT,Absorption,Solvatochromism
更新于2025-09-23 15:23:52
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A photochromic benzothiadiazole-diarylethene with tuneable on-off fluorescence modulation
摘要： Organic molecules with photoswitchable emission properties are of interest in the optical devices field. We present herein in-solution studies for two dimethoxy-DTE-fluorophore-conjugates with carboxylic acid anchor group attachable to semiconductor surfaces (DTE-BODIPY and BTD-DTE). Both conjugates show almost quantitative reversible photoisomerization between open (OF) and closed form (CF). With excitation of the fluorophores, both conjugates emit fluorescence with highly solvent dependent OFs (BTD-DTE > DTE-BODIPY) and minor solvent dependent CFs. In the polar solvent MeCN for BTD-DTE a TICT state is clearly observed, which will be located in the twisted conjugated structure of the benzoic acid-BTD-fluorophore-methoxy thiophene unit. BTD-DTE shows positive solvatofluorochromism with decrease of fluorescence quantum yields by increasing Δf verified in Lippert-Mataga plots. This leads to solvent dependent on-off/off-on (CF-OF) emission modulation by FRET with well-separated emission bands for BTD-DTE.
关键词： Diarylethenes,Photochromism,Solvatochromism,Fluorescence,Energy transfer
更新于2025-09-23 15:22:29
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Solvatochromism of Quinoline-390 and Rhodamine-800: Multiple Linear Regression and Computational Approaches
摘要： The electronic absorption and emission spectra of laser dyes quinoline-390 and rhodamine-800 in distinct organic solvents have been analyzed to understand conventional interactions of solvents on the intensities, peak positions of both absorption and emission spectrum. The relationship between absorption spectrum (λmax) and solvatochromic constants (ε, n, E) indicates that the peak positions are fundamentally influenced by non-specific and specific kind of interactions between the solute and solvent. Solvent effects on the electronic absorption band shift are characteristics of the degree of charge rearrangement of the solute molecules upon electronic excitation. These spectral shifts reflect the effect of the equilibrium solvents association across the energized solute particle, which adjusts inertially as a result of quick charge realignment upon radiative deactivation to the lowest electronic state. Spectral regression study techniques were carried out for the qualitative chemical analyses of these compounds, which provides an opportunity to assess electrical-optical molecular constants within the excited electronic conditions. Further TD-DFT computational techniques for optimized geometry, electronic structure and Mulliken charge distribution in vacuum and ethanol solvent were carried out to acquire additional knowledge of the molecular arrangement and electronic properties of these laser dyes.
关键词： Quinoline-390,Regression Correlations,Mulliken charges,TD-DFTQM analysis,Solvatochromism,Rhodamine-800
更新于2025-09-19 17:15:36
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AIE active piperazine appended naphthalimide-BODIPYs: photophysical properties and applications in live cell lysosomal tracking
摘要： Piperazine appended naphthalimide-BODIPYs (NPB1–NPB4) exhibiting solvatochromism and aggregation-induced emission with a large Stokes shift (up to 146 nm) have been described. Separation of naphthalimide and BODIPY fluorophores by piperazine in these conjugates creates a donor–acceptor system and induces twisted intramolecular charge transfer, in addition to photoinduced electron transfer. The crucial role of naphthalimide, the alkyl chain length, the piperazine ring, and the solid-state packing on AIE has been extensively investigated by various studies. Superior cell permeability coupled with bio-compatibility of these conjugates offers a unique opportunity for their potential applications in live cell lysosomal tracking.
关键词： solvatochromism,piperazine,naphthalimide,lysosomal tracking,BODIPY,AIE
更新于2025-09-19 17:15:36
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Diarylpyrazine-based position isomers: A detailed study of optical properties and structure-property relationship
摘要： A versatile and expeditious synthetic route to pyrazine-based symmetric and asymmetric chromophores decorated with donor-acceptor (D-A) has been designed to study their structural effects on optical properties. Suzuki-Miyaura coupling of dihalopyrazine with various aryl boronic acids was synthesized under microwave condition. Pyrazine functionalized at C-2, C-5 and C-6 serve as acceptor to construct linear and angular push-pull chromophores. The photophysical, electrochemical and thermal properties of all the target chromophores were systematically investigated and the results were correlated theoretically by density functional theory computations. The emission wavelength was significantly red-shifted by introduction of strong electron withdrawing group (CN). The permutation of terminal donor acceptor units tunes the optoelectronic properties in a predictable way, aiding in the rational design of small molecule for luminescent materials. These chromophores displayed multicolor change in different solvents, exhibiting good solvatochromism with a large Stokes shift.
关键词： solvatochromism.,cross-coupling,Diarylpyrazine,intramolecular charge transfer
更新于2025-09-19 17:13:59
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Acid mediated tunability of stimulated laser emission from dye doped chiral microdroplets
摘要： In the last decade, the possibility to use liquid crystal droplets as optical micro-cavities and lasers has attracted much attention since it paves the way for many applications in the field of sensors or tunable photonics. Several techniques can be used to obtain small micro-resonators as, for example, dispersing a cholesteric liquid crystal inside an immiscible isotropic fluid to create an emulsion. Since liquid crystals are extremely sensitive to external factors as temperature or external fields, laser tuning can be easily achieved. Here, we report on the possibility to tune the laser emission from dye doped cholesteric liquid crystals microdroplets dispersed in a glycerol matrix in presence of nitric acid molecules in the emulsion. Using a fluorescent dye with pH dependent optical properties, the emitted laser wavelength can be tuned in a range of 60 nm. This effect could find applications for the development of spectroscopy based sensors.
关键词： Microdroplets,dyes,cholesteric liquid crystals,laser tuning,solvatochromism
更新于2025-09-12 10:27:22
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Pyrene Based NLOphoric D‐π‐A‐π‐D Coumarin‐Chalcone and Their Red Emitting OBO Difluoride Complex: Synthesis, Solvatochromism, Z‐scan, and Detailed TD‐DFT Studies
摘要： NLOphoric D-π-A-π-D coumarin chalcone 5 and their BF2 complex 6 were designed, synthesized and characterized through Mass,13C-NMR, and 1H-NMR analysis. Their Photophysical properties are extensively studied in solvents of different polarity. On BF2 complexation of coumarin chalcone shows highly red shift in absorption and emission spectra compared to uncomplexed coumarin chalcone. Positive solvatochromism observed which is well supported by linear and multilinear regression analysis. For BF2 complexed coumarin-chalcone 6 the solvent dipolarity (CSdP) is the main factor responsible for slightly red shift in absorption spectra, and also for the highly red-shift in emission spectra. Frontier molecular orbital, molecular electrostatic potential and Generalized Mulliken-Hush analysis revealed intramolecular charge transfer in these compounds. Nonlinear optical (NLO) properties for compounds 5 and 6 were studied by solvatochromic and computational method. The linear polarizability (α), first-order hyperpolarizability (β) and second-order hyperpolarizability (γ) of compounds were studied by the time dependent density functional theory using three different functionals namely B3LYP, BHHLYP and CAM(cid:0) B3LYP with the 6–31 G (d) basis set. BF2 complexed compound 6, show higher values for αe + αv as well as βe+βv compared to compound 5. Third order nonlinear optical susceptibility (χ(3)) of these compounds obtained by Z-scan analysis. Third-order (χ(3)) non-linear optical properties of BF2 complexed coumarin-chalcone 6 were observed to be several times higher than those of the uncomplexed coumarin-chalcone 5 these justify the design approach.
关键词： NLOphoric,Z-Scan,positive solvatochromism,pyrene-chalcones,TD-DFT,solvatochromic NLO
更新于2025-09-11 14:15:04
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UV-light intervened synthesis of imidazo fused quinazoline and its solvatochromism, antioxidant, antifungal and luminescence properties
摘要： The photochemical preparation of benzo[4,5]imidazo[2,1-b]quinazoline was assessed under the illumination of UV wavelength (>360 nm). The compound 3,4-dihydronaphthalen-1(2H)-one 1 with 1H-benzo[d]imidazol-2-amine 2 in the existence of KOH/DMF which lead to the aromatized compound 3. The notable remark of this reaction is that the UV irradiation (312 nm) plays a vital part in the formation of the compound, 3 in shorter duration (2h) which resulted in the reaction gave was higher yield (96%). Compound 3 was analyzed by H1, C13 NMR, and HRMS. Solvatochromism impacts of the compound 3 was computed with deference (DCM < methanol< DMF < DMSO). The compound, 3 was presented to invitro free radical screening utilizing DPPH strategy and furthermore H2O2 technique. The standard ascorbic acid has less IC50 value esteem than compound 3. Further, it was subjected to in vitro fungicidal action against two Aspergillus species (A. flavus & niger). The anti-fungal activity of compound 3 additionally demonstrated great action, when compared antifungal specialist Fluconazole.
关键词： solvatochromism,DPPH,UV radiation,anti-fungal,H2O2,antioxidant,Imidazo[2,1-b]quinazoline
更新于2025-09-10 09:29:36
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Tetrakis(oxadiazolylphenyl)pyrazines: New St. Andrew's Cross- Shaped Liquid Crystals
摘要： π-Conjugated molecules with the shape of St. Andrews cross have been synthesized via fourfold Huisgen reaction. Four 2,5-diaryl-1,3,4-oxadiazol arms are attached to a central pyrazine nucleus. These fluorescent stars, when decorated with a rim of eight alkoxy side chains are discotic liquid crystals. Depending on the substitution pattern, the width of the liquid phase varies within a broad range of 25 °C to 250 °C. In their liquid crystalline phase, the molecules assemble in a typical hexagonal columnar supramolecular arrangement.
关键词： solvatochromism,liquid crystals,WAXS,POM,pyrazine
更新于2025-09-10 09:29:36